Botulism is a fatal disease, often involving the ingestion of food contaminated with Clostridium botulinum neurotoxins (BoNTs). In this work a novel gold nanoclusters synthesized and applied as a biocompatible bed for immobilization of aptamer on the screen printed gold electrode surface to fabrication of Impedimetric aptasensor for sensitive and without need to label BoNT serotype A in some real samples. Successful synthesis of nanoclusters were confirmed by using transmission electron microscopy, UV-Vis and florescence spectroscopy. Also fabrication of aptasensor was followed by cyclic voltammetry and electrochemical impedance spectroscopy methods. The impedance changes, due to the specific interactions at the aptasensor surface that efficiently restricted the electron transfer of redox probe [Fe(CN)6] 4-/3- were utilized to detect of the toxin. The measurements were highly targeted specific and linear with BoNT/A concentrations in the range of 0.41-500 pg ml-1 and associated with a detection limit of 0.125 pg ml-1
